Electric circuit breaker arc chute with arc discharge filter



June 3, 1969 E. a. HEFT 3,448,231

ELECTRIC CIRCUIT BREAKER ARC CHUTE WITH ARC DISCHARGE FILTER Filed Nov. 14, 1966 Sheet of 3 FIG. 1 W

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United States Patent 3,448,231 ELECTRIC CIRCUIT BREAKER ARC CHUTE WITH ARC DISCHARGE FILTER Eldon B. Heft, West Hartford, Conn., assignor to General Electric Company, a corporation of New York Filed Nov. 14, 1966, Ser. No. 594,048 Int. Cl. H01h 9/30, 33/58, 33/04 US. Cl. 200-144 13 Claims The present invention relates to electric circuit breakers and more particularly to electric circuit breaker arc chute constructions for such circuit breakers which include, in addition to the arc cooling and extinguishing means required for electrical reasons, are discharge filter means for reducing the intensity of sound generated by the interruption for dissipating the shock wave generated thereby, and for preventing the emission of flame and/ or incandescent gases therefrom.

Electric circuit breakers of high interrupting capacity, and particularly electric circuit breakers of the currentlimiting type, are required to operate at exceedingly high speeds. This requires that an are be created at extremely high speed and elongated and driven into the arc cooling and extinguishing means at extremely high speed. When this is done at the speeds required for currentlimiting interruption, the interruption process is accompanied by a number of outward effects which, although not interfering with the electrical performance of the circuit breaker in its current-limiting interruption, are nevertheless objectionable for other reasons.

Thus for example, it has been found that a high capacity current-limiting circuit breaker, capable of operating at commercial power voltages and current ratings, such for example as 50 or 100 amperes at 600 volts, and capable of interrupting short-circuit currents generated by power systems having capacities of 100,000 or more amperes, the following objectionable outward manifestations of the interruption are produced: (a) a tongue or jet of incandescent hot gases is emitted from the outlet of the circuit breaker a distance of three feet or more; (b) an explosive sound report is produced comparable to that produced by a fair-sized explosion, such sound report being of such a magnitude as to be not only uncomfortable but even dangerous to the ears of personnel in the immediate vicinity; (c) a compressive shock wave in air is generated of substantial magnitude.

Various structures have been utilized in accordance with the prior art for the purpose of cooling the hot arc gases before they are expelled from an arc extinguishing chamber as well as for protecting against strikeover across the outlet of the arc chute. While these structures have been proposed and utilized for circuit breakers of substantial rating, none of such prior art circuit breakers have presented a problem of the degree of severity as that involved in the structure to which applicants efforts are directed. Most of the prior art devices, moreover, have been concerned with the aspects of preventing damage to external articles by the hot gases emerging from the circuit breaker and with preventing flash-over at the exit of the arc chute, rather than in diminishing the magnitude of the sound developed and dispersing the shock wave generated.

It is an object of the present invention to provide an electric circuit interrupting device including an are discharge filter structure which substantially completely eliminates incandescent arc gases external of the circuit breaker.

It is another object of the invention to provide an electric circuit breaker including an arc discharge filter or mufile device which greatly reduces the magnitude of the externally perceptible sound generated by a current-limiting circuit interruption.

It is a further object of the invention to provide an electric circuit breaker of the type described including an arc discharge filter or mufiie which is capable of dispersing and reducing the severity of the compressive shockwave developed in a current-limiting type circuit interruption.

It is a further object of the invention to provide an electric circuit breaker including an arc discharge filter or rnufile device of the type described above which does not have any deleterious effects upon the current-limiting performance of the arc extinguishing portion of the circuit breaker proper, and particularly one which does not create a reflected back-wave of pressure by reason of obstruction of the otherwise open exit portion of the circuit interrupter.

It is a further object of the invention to provide an electric circuit interrupter of the multi-pole type comprising at least three pole chambers in side-by-side relation and including arc discharge filter means operable to perform the functions described above from each of the three poles of the circuit breaker and further comprising means for successfully containing the substantial pressures generated within the arc chambers.

Other objects of the invention will in part be pointed out and in part become obvious from the following detailed description of the invention, and its scope will be pointed out in the appended claims.

In accordance with the invention, an electric circuit interrupter is provided of the type including arc initiation means of the high speed or current-limiting type, and means for rapidly elongating the arc and creating a substantial voltage drop thereacross to oppose the driving voltage of the circuit and to reduce the current in the arc to zero in exceedingly short time. For this purpose the circuit breaker includes an arc initiation chamber and an adjoining arc extinguishing chamber containing a pair of diverging arc runners along which the arc is moved and elongated at high speed. The are runners terminate adjacent an arc baffle assembly containing relatively restricted slot-line diverging outlet openings through which the arc gases are propelled. The are creation and elongated apparatus may, of corrse, take various forms. Certain aspects of the particular structure disclosed herein are disclosed in greater detail and claimed in co-pending application 592,443 filed Nov. 7, 1966 and assigned to the same assignee as the present invention.

Supplementing the aforesaid arc initiation and extinguishing chambers and restricted baflle assembly, I provide an arc discharge filter assembly or muffle, comprising a series of four serially-related chambers. The first of these chambers comprises a pre-cooler" structure of metallic plates extending in the same direction as the motion of gases emerging from the are extinguishing baffle assembly. The pre-cooler plates termimate in angularly outwardly diverging or fanned end portions called deflectors which effectively serve to prevent the reflection of the arc gases from the plates of the succeeding section back into the arc extinguishing chamber and interfere with the arc-extinguishing functioning of the circuit interrupter. The pre-cooler portion is followed by a first expansion chamber, serving to further assist the break-up of any reflected back-wave and to introduce some turbulent action into the gas flow pattern.

This assembly is supplemented by a first cooler assembly comprising an assembly of metallic girds or plates extending transversely to the direction of travel of the gases and having a large number of relatively small holes therein. Adjacent ones of these girds or plates are spaced by insulating spacers, and the holes of adjacent metallic plates are non-aligned or staggered. The third chamber is an expansion chamber allowing some expansion of the gases and random movement thereof, tending to a) break-up any sharply defined flow patterns. The expansion chamber is followed by a second cooler assembly of the same general construction as the first cooler assembly. The cross-sectional area of the entire arc extinguishing chamber is divided into two longitudinal sections by an insulating divider plate extending along the longitudinal center line of the outlet path. Each outlet path thus created includes chamber constructions as just described. In addition, each of the expansion chambers referred to includes a longitudinal barrier dividing plate.

In order to provide adequate strength to resist the pressures generated internally, especially in a multipole form without requiring a large amount of space, a 3-compartment steel casing or jacket is provided having a chamher for each pole and having an end wall, with openings for the arc gases to exit through.

The invention will be more fully understood from the following detailed description, and its scope will be pointed out in the appended claims.

In the drawings:

FIGURE 1 is a side elevation view of an electric circuit interrupting device incorporating the invention, a portion of the side wall thereof being removed to show the internal construction;

FIGURE 2 is a schematic representation of the circuit through a complete circuit breaker of one type inconporating the invention;

FIGURE 3 is a top plan view of a three-pole circuit interrupting device including an arc extinguishing means and an arc discharge filter assembly constructed in accordance with the invention;

FIGURE 4 is a side elevation view of the three-pole arc extinguishing means and one discharge filter assembly of FIGURE 3;

FIGURE 5 is an. end elevation view of the three-pole arc extinguishing means and are discharge filter assembly of FIGURES 3 and 4;

. FIGURE 6 is an exploded perspective view of a precooler portion of the arc discharge filter assembly of the circuit interrupter assembly of FIGURE 1;

FIGURE 7 is an exploded perspective view of the arc discharge filter and mulfie assembly of the device of FIGURE 1;

FIGURE 8 is a partially exploded perspective view of the parts utilized in the cooler assembly portion of the arc discharge filter and muffle assembly of the device of FIGURE 1, and

FIGURE 9 is a fragmentary sectional view of a modified form of the invention.

In the drawings, the invention is shown as incorporated in a three-pole electric circuit breaker or interrupter. As shown in diagrammatic form in FIGURE 2, each pole of the interrupter comprises an arc extinguishing section 10, a movable contact operating means 11, and are discharge filter or muffle assembly 12.

Referring now to FIGURES 1 and 2, the arc extinguishing portion 10 of the interrupter comprises a pair of spaced, angularly disposed stationary contacts 13 and 14, mounted on a pair of outwardly diverging are runners 15 and 16 respectively, which terminate in arc anchor tips 17 and 18, respectively.

A generally wedge-shaped movable contact assembly 20 is also provided having a pair of contact members or contact surface portions 21, 22 thereon disposed at an angle to each other for cooperating with the stationary contacts 13 and 14 respectively. The movable contact member 20 is connected by a contact operating rod 24 to the plunger 25 of a solenoid 26 (see FIG. 2).

The solenoid 26 is connected electrically in series with a first blow-out coil 27, the stationary and movable contact assembly, a second blow-out coil 28, and then to an output terminal 29. The other end of the solenoid 26 is connected to an input terminal 30. Blowout coils 27, 28 are not shown in FIGURE 1, but may be positioned adjacent the contact assembly and provided with magnetic (pole pieces which concentrate the magnetic flux across the path of the arc to assist acceleration of the arc in its elongating direction.

The circuit breaker also includes means for manually moving the movable contact assembly between open and closed circuit positions and for retaining it in the closed circuit position in such a way that when the solenoid 26 is energized, the movable contact member may be pulled to the open condition despite the retention of the operating handle in its on position. For this purpose, there is provided a mechanism which may take any desired one of a number of different forms. For the purpose of illustration, a simplified operating mechanism is shown connected to the contact operating rod 24 and comprising an operating link 32 pivotally supported on a fixed pivot 33, and having an elongated slot 34 therein receiving a pin 35 carried by the rod 24. An operating handle 36 is supported for arcuate movement between on and off positions as shown, and a tension spring 37 is connected between the operating handle 36 and the pin 32A.

The handle 36 may be supported for arcuate movement in the manner described by any suitable means, such, for example, as being supported in an arcuate track, not shown, in insulating side wall members, not shown. Alternatively, the handle 36 may be supported on a rigid generally U-shaped handle support member, not shown, having its pivot point below the link 32, and substantially in vertical alignment with the pin 33.

It will be observed that when the operating handle 36 is moved from off position to on, the line of action of the spring 37 passes across the pin 33, and biases the operating link 32 in counterclockwise direction, moving the operating rod 24 to the right, moving the movable contact assembly to closed position. When the parts in the closed circuit position, the bias of the spring 37 urges the movable contact to its closed position providing contact pressure between the movable contacts 21, 22 and the corresponding stationary contacts 13, 14. When the parts are in this condition, if a short-circuit occurs in the line connected to the circuit breaker and excessive current flows therethrough, the solenoid 26 increases its pull on the plunger 25, pulling the contact operating rod 24 and the movable contact assembly 20 to the left as viewed. This action causes the link 32 to rotate in clockwise direction, regardless of whether the operating handle 36 is forcibly restrained in the on position or not. If desired, the dimensions and proportions of the parts may be arranged so that when the movable contact rod moves to open circuit position, the line of action of the spring 37 will have passed across the pivot pin 33, thereby causing the link 32 to remain in open circuit position if the handle member 36 is not forcibly restrained, thereby moving the handle member back toward off position. A mechanism suitable for use with the invention is shown and described in greater detail in application Ser. No. 457,557 filed May 21, 1965, and assigned to the same assignee as the present invention.

As the movable contact assembly 20 moves to open position, a pair of short arcs, not shown, are drawn between the movable contact 21 and the stationary contact 13 and between the movable contact 22 and the stationary contact 14, respectively. These two shorts arcs are immediately transformed into a single longer are extending between the stationary contacts 13, 14, as indicated in FIGURE 1. This are is thereupon moved by its own magnetic motoring action, supplemented by the magnetic blow-out force of the coils 27, 28 and by the force of arc gases, outwardly along the arc runners 15, 16.

When the arc is created and elongated in the manner described at extremely high speeds as required for true current-limiting action, high pressures are generated within the arc extinguishing chamber 38. The circuit interrupter includes an exit baffle member 39 extending across the outlet portion of the arc chamber 38, having two sets 39A, 39B, of angularly-diverging slots therein for permitting controlled venting of the gas from the circuit interrupter per se. The temperature and speed of arc gases emerging from the openings 39A, 39B of the baffle 39 are extremely high, and of such a nature as to be intolerable in situations in which personnel may be nearby at the time of a short-circuit interruption or where the breaker must be located near an object which might be damaged by such hot gases.

In accordance with the present invention, a combined arc discharge filter and noise and flame muffle assembly is provided which effectively eliminates the objectionable expelled flame and hot gases and greatly reduces the noise generated by the interruption process.

Referring first to FIGURE 3, the arc discharge filter or flame and noise muflle'of the invention includes a generally rectangular box-like heavy metallic enclosure 40 having opposed side walls 41, 42, and a pair of intermediate barrier Walls 43, 44, dividing the general enclosure into three compartments 45, 46, 47. The enclosure 40 also includes an integral end wall 65, having a plurality of rectangular apertures 66 therein. Each of the chambers 45, 46, 47, contains arc discharge and filter apparatus all of which are similar, and therefore the structure of the apparatus contained in only one chamber, i.e., chamber 47, will be described, it being understood that the chambers 45, 46 also contain comparable structure.

Referring now to FIGURE 4, the chamber 47 is divided by longitudinal barrier means comprising barriers 49A and 49B and 49C together with intermediate barrier portion 50A of the insulator block 50 to be described into two parallel elongated generally rectangular chambers 47A and 47B. Each of the longitudinal portions 47A, 47B of the chamber 47 contains similar arc discharge filter and muflle structure, and therefore the parts contained in only the lower portion 47B will be described, reference being had for this purpose to the lower portion of FIGURE 1.

As indicated in FIGURE 1, the portion 47B of the arc discharge filter and muffle assembly includes five (5) serially related chambers or portions. These portions are as follows: 1) a pre-cooler or preliminary heat exchange portion 51, (2) a combination first expansion chamber and reflective wave dispersing or diffusion means 52, (3) a first cooler portion 53, (4) a second expansion and diffusion chamber 54, and (5) a final cooler chamber portion 55. The construction and assembly of the parts contained in these chambers will now be described in detail with reference to the exploded views FIGURES 6 and 7.

Referring to FIGURES 6 and 7, the pre-cooler portion 51 comprises a pair of supporting plates 57 supporting a plurality of spaced stacked relatively short metallic plates 58A. Adjacent each of the plates 58A except the end plates, and preferably in side-to-side contact therewith, is a second, longer plate 58B having an angularlybent end portion 58B. This combination provides plates which are of substantial thickness and therefore of substantial heat absorbing capacity throughout their major portion, and deflector portions which extend into the adjacent expansion chamber 52 while occupying only a minimum amount of the space in the expansion chamber. The plates 58A, 58B are spaced and arranged so that the spaces between these plates are in alignment with the spaces 39B in the baffle member 39.

The construction of the first cooler portion 53 is shown in exploded FIGURE 7, and also in detail in FIGURE 8. Each of the assemblies 53 includes a series of metallic plates 60 having a large number of small. holes 61 therein. The metallic plates 60 are maintained in close spaced relation by insulating spacer members 62 each comprising a generally rectangular frame portions 62A and an intermediate portion 62B. The spacer members 62 are constructed of any suitable insulating material having the ability to withstand high temperatures. In a preferred form of the invention, the insulating spacer 62 comprise an impregnated cellulosic fibre known as vulcanized fibre.

Adjacent metallic plates 60 have the holes 61 therein offset or staggered with respect to the holes 61 in each of the adjacent plates. As a result, there is no continuous straight-line path for gases through the assembly of plates 53. The assembly of plates 60 and spacers 62 is retained in assembled relation primarily by means of the cooperation of the adjacent parts and the fact that all of such parts are closely fitted within the corresponding chamber of the generally box-like enclosure 40, and maintained therein by the retaining relationship of the barrier 39. For the purpose of facilitating handling and assembly, however, the plates 60, 62 may be retained temporarily in assembled relation by means of non-conductive adhesive strips 63.

The second expansion chamber 54 is formed by two chambers 54C and 54D of an insulating block 50. The insulating block 50 is preferably constructed of insulating material having the characteristics of high heat withstand-ability and substantial strength. A suitable material for example has been found to be glass fiber filled alkyd or melamine plastic.

In FIGURE 9 there is shown a modified form of second expansion chamber means 54. In this form of the invention, expansion chambers 54A, 54B, 54C, and 54D are provided by a pair of generally U-shaped metallic members 74 and 75 respectively. These pieces interfit in such a manner that their upturned leg portions 74A, 74B and 75A, 75B, together with the intermediate partition member 50A, form the dividing partition and end walls of the aforesaid chambers. In this form, the walls are constructed of metallic material for further helping to extract energy from the arc gases. As previously mentioned, because this location is so remote from the point of initiation of the arc, there is no danger of arc strikeover at this point.

The final cooler assembly 55 is constructed in the same manner as the preliminary cooler 53 previously described, but preferably includes fewer plates.

Each of the chambers 45, 46, 47, of the enclosure 40 is provided with insulating liner means comprising a pair of closely interfitting generally rectangular sleeves or liner members 67, 68, see FIGURE 7. Each of these members is formed from a flat sheet of insulating material having its edges abutting together to form a seam such as the seams 67A of the member 67 and 68A of the member 68. These seams are preferably arranged so as to be non-adjacent when the parts are in assembled relation.

In assembly, the housing member 40 with its barriers ,43, 44 is first constructed, and the liner members 67, 68 are inserted in each of the chambers 45, 46, 47. The are discharge filter and mufl le members described above are then inserted into these chambers respectively beginning with the final cooler assemblies 55, the second expansion chamber members 50, the first cooler assemblies 53, the pre-cooler and diffuser assemblies 51, and finally the arc barrier block 39. The barrier block 39 is retained in place by cross-pins or insulated bolts such as bolts 71A, 71B, covered by insulating tubes 70, with suitable retaining means, not shown, at each end.

The side walls 41, 42 and the intermediate Walls 43, 44 of the enclosure 40 are extended at the arc extinguisher end of the assembly, and provide means for anchoring and assembling the insulating blocks 72 forming the enclosure for the arc initiation and extinguishing portions.

Having described in detail the construction and assembly of the arc discharge filter and muffle assembly of the invention, the operation of the device will now be discussed. It should be understood that while considerable advances in the knowledge of the behavior and methods of control of arcs in gaseous media are continually being made, as witnessed by the aforementioned patent application 457,557 assigned to the same assignee as the present invention, the subject is by no means completely understood in all its ramifications. The same is generally true of the subject matter of arc discharge filter and muffle designs, and perhaps even more so of the interrelation and cooperation of these two components. The following observations are based, however, upon numerous experiments and tests in which the apparatus described above has been found to be exceedingly effective. Accordingly, while the particular mechanisms or phenomena operating in the device may not be completely understood, the following is the best present interpretation of the inventor as to the functioning of the apparatus in achieving desirable results attained.

It is believed that the preliminary heat exchange portion 51 functions to extract a substantial amount of heat from the incandescant gases emerging from the barrier member 39 as these gases are forced to pass in close contact with the relatively cold metallic surface of the plates. This action may descriptively be referred to as a scrubbing action, and causes an important decrease in the energy of the arc gases. The efficiency of efiicacy of this action is critically related to the spacing between adjacent walls of the plates 58A, 58B, which is another reason why the thickness of these plates is made greater at their main body portion.

The outer ends of the plates 58B are directed at an angle to the main portion or fanned primarily to prevent occurrence of a reflected back-pressure wave which might otherwise be reflected from the surface of the first of the plates 60 of the assembly 53. In addition, these diverging portions-or diffusers introduce a desirable turbulence at this point causing the cooler portions of the gas, which have been cooled by contact with metallic plates 58A, 58B, to mix with the remaining gases and more equally distribute the heat.

The divider 49, and particularly the divider portion 49A, prevents the are from striking across, either at the beginning or at the ends of the plates 58A, 58B. It will be observed that in order for an arc to strike across through this part of the arc extinguishing assembly with the present construction, it would have to extend, from the stationary contact 17, through at least one of the slots 39A, to the spaces between the plates 58A, 58B, around the ends of these plates, toward the divider plate 49A, thence back through one of the spaces between the plates 58A, 58B, through another one of the slots 39A, then back through one of the slots 39B, and through a similiar path between the plates 58A, 58B in the lower section, around the ends of the plates in this section, to and finally back through another one of the slots 39B to the stationary contact 18. Such a path would be so long that its total voltage drop would far exceed the voltage drop being maintained in the are directly between the stationary contacts 17 and 18 at the surface of the insulating block 39. If the conditions are being considered as they exist immediately after the extinction of the arc between the contacts 17, 18, the voltage of such an alternate parallel path could be so high as to exceed the voltage required to breakdown directly between the stationary contacts 17, 18.

The are gases are forced through the assemblies 53 previously described comprising a series of spaced metal plates 60 having a large number of relatively small holes 61 therein and maintained in closely spaced relation by the insulating spacers 62. As previously noted, the holes 61 in these plates are not in exact alignment, so that there is no straight-through path through this assembly of plates. The hot gases are therefore forced into contact with the metallic material of the plates at a great many points, since as the jets of gas emerge through the openings in any one particular plate they immediately impinge against the metallic material of the next adjacent plate. Because of the spacing between adjacent plates, a degree of turbulence is created which causes inter-mixing of the incandescant gases and accelerates and improves the cool- The spacers 62 may be constructed of any desirable insulating material which is capable of withstanding the heat created by the are. If desired, the spacer 62 may be constructed of metallic material, since at this stage of the arc extinguishing assembly, an arc path of adequate length is provided in any case, and there would be no danger of strikeover, it being noted that the lower assembly 53 is divided from the upper assembly 53 by the barrier plate 49B.

The block 50 provides a total of four (4) expansion chambers therein, as shown particularly in FIGURE 7, 54A, 54B, 54C and 54D. These chambers are made of substantial length as compared to the spaces between the plates 60, for the purpose creating further turbulence and for removing or filtering out relatively low frequency shock and sound waves (the filter assemblies 53, on the other hand, with the relatively close spacing of the plates 60 serve to remove, damp, or reduce the relatively high frequency shock and sound waves). A series of 4 of such chambers are provided, rather than one or two continuous large chambers in order to adjust the volume of each of the chambers to the size best suited to cancel or reduce the frequencies in the lower range desired to be eliminated by this section. The final section 55 is similar to the previous section 53 and serves to further reduce the noise, flame, and shock wave. In addition, the presence of the final section 55 is believed to be desirable in connection with obtaining the proper action from the expansion chambers 54.

In accordance with another aspect of the invention, the enclosure 40 provides a separate casing or enclosure for each of the arc discharge filter and muflle assemblies of each of the poles of the circuit breaker. As previously described, the enclosure 40 preferably comprises a single integral box having an end wall 65 with a series of generally rectangular openings 66 therein, see FIGURE 5. Each of the openings 66 corresponds in area to the crosssectional area of one of the expansion chambers 54A, 54B, 54C, 54D. Thus the outlet opening area of the assembly not decreased by the end wall 65, but nevertheless the end wall 65 serves to provide a substantial support in this direction to prevent the parts from blowing outwardly under the pressure of the arc gases. In addition, the fact that the side walls of the container 40 which extend perpendicular to the bottom wall are all integrally interconnected, and this assembly is reenforced and held together by a number of transversely extending assembly bolts 71. These comprise a series of three main bolts 71A disposed along the longitudinal center-line of the assembly, and a series of additional bolts 71B adjacent the arc initiating chamber.

The are discharge filter and muffle assembly of the invention has been found highly effective in reducing the noise, shock wave, and flame emitted from a high pressure circuit interrupter. While it has not been possible to obtain specific comparative data on the magnitude of the reduction, it is believed that a conservative estimate in reduction of the force of the sound and shock wave is in the order of 1000 to 1.

By means of the invention, an electric circuit interrupter is provided which has relatively small size compared to extremely high capacity interruption ability. For

example, the embodiment illustrated provides a circuit interrupter having a normal current carrying rating of amperes at 600 volts, and is capable of interrupting the short-circuit current created by a system which has the capability of delivering over 100,000 amperes. The outer dimensions of this circuit breaker, including the arc filter and discharge and mufiie portions is approximately 17 inches long and 4 /2 by 4% inches cross-section. Prior to the development of applicants present invention, there was no circuit breaker capable of performing a current-limiting interruption on a circuit of this magnitude. The dimensions of a prior art non-currentlimiting circuit breaker which were of a type which would be required to be used in circuits having these power capabilities are as follows: 33 inches lOng, With a crosssectional area of approximately 27 by 25 inches, giving a total volume over 60 times as great as the breaker of the present invention.

While the invention has been disclosed in one particular embodiment, it will be apparent that many modifications thereof may readily be made without departing from the spirit and scope of the invention. It is accordingly intended by the appended claims to point out the particular areas considered to comprise the essence of applicants novel and useful contribution to the art and to cover all such modifications as fall Within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit interrupter comprising means for establishing an arc and are discharge mufiie means, said are discharge muffle means comprising:

(a) a first heat exchange portion comprising a plurality of relatively closely spaced flat metallic plates extending parallel to each other in closely spaced relation in a row, each of said plates extending parallel to the direction of flow of gases from said arc whereby said are gases are constrained to pass between said plates in close thermal contact with adjacent side surfaces of said plates;

(b).a plurality of arc diffuser plate portions, said arc diffuser portions comprising a series of fiat sheet metallic members extending at an angle to said plates of said first heat exchange portion and closely adjacent the exit point for gases passing between said first heat exchange plates whereby gases passing between said heat exchange plates strike said diffuser plate members and are caused to assume a turbulent condition for intermixing cool portions of said gas with more heated portions thereof, and

(c) a combined cooling and mufiling portion in the path of movement of said are gases adjacent said are diffuser plates, said combined cooling and mullling portion comprising a series of generally planar metallic plates each having a large number of relatively small holes therethrough and means supporting said plates in parallel closely-spaced relation in a row, said plates each extending transversely of said are gas exit path, said holes in adjacent ones ofsaid cooling and muffling plates being out of alignment with each other, said means supporting said plates in spaced relation providing spaces between said plates for expansion of said arc gases and for absorbing and dispersing sound and shock waves.

2. An electric circuit interrupter as set forth in claim 1 wherein said are diffuser members have a thickness substarrtially less than said plates of said first heat exchange portion.

3. An electric circuit interrupter as set forth in claim 1 wherein said are discharge muffle means also comprises a first expansion chamber between said first heat exchange portion and said combined cooling and mufiiing portion, said are diffuser members being positioned within said first expansion chamber.

4. An electric circuit interrupter as set forth in claim 1, wherein said are diffuser members comprising integral extension portions of said preliminary heat exchange portion plates.

5. An electric circuit interrupter as set forth in claim 1, wherein said circuit interrupter also comprising a second expansion chamber immediately following said combined cooling and mufiling portion, said second expansion chamber having a dimension in the direction of arc gas travel substantially greater than said spacing between said plates of said combined cooling and mufliing portion.

6. An electric circuit interrupter as set forth in claim 1,

wherein said are discharge mufile means also include a second expansion chamber following said combined cooling and mufliing portion, said second expansion chamber having a dimension in the direction of arc gas flow at least 5 times the spacing between said plates of said coolermuflie portion.

7. An electric circuit interrupter as set forth in claim 1, wherein said means for establishing an arc comprises:

(a) at least one pair of relatively widely spaced stationary arc terminal portions and means for creating said are between said spaced arc terminal portions, and are baffle means extending between said are terminal portions having a plurality of relatively thin slot-like openings extending therethrough and having exit portions at a side thereof opposite said are terminal portions said circuit interrupter also comprising means enclosing the space between said are terminal portions so that said slot like openings comprise essentially the only exit path for are gases created between said are terminal portions, and

(b) said are discharge muflle means being assembled and positioned with respect to said means for establishing said are so that said first heat exchange portion plates are maintained with an edge portion thereof substantially in contact with said baffie member whereby said are gases emanating from between said arc terminal portions are constrained to pass through said slot like openings and directly into the spaces between said preliminary heat exchange plates.

8. An electric circuit interrupter as set forth in claim 7, wherein said first heat exchange portion said diffuser plate portion and said combined cooling and mufiling portion are each divided by partition means extending substantially parallel to said first heat exchange portion plates and on a line extending substantially midway between said spaced arc terminal portions and having one edge portion thereof abutting against said bafiie means, whereby the exit paths for are gases emerging from said bafile are divided into two groups of paths, the paths of each group being maintained separate from each other from said baffie at least to the exit point from said combined cooling and mufiling portion by said barrier means.

9. An electric circuit interrupter as set forth in claim 8, said circuit interrupter also comprising a second expansion chamber immediately following said combined cooling and muffling portion, said second expansion chamber comprising a multi-compartment chamber, said compartments being defined by parallel extending portions of a first generally U-shaped metallic member and a second generally U-shaped metallic member, said second .U-shaped metallic member having its bight portion in opposed relation to the bight portion of said first U-shaped metallic member and having the leg portions of said U within and between the corresponding leg portions of the first U-shaped member, and a partition member between said leg portions of said second U-shaped member, whereby said leg portions of said first and second U-shaped members and said partition member, in combination with said generally rectangular enclosure means define four generally rectangular expansion chambers each being in alignment with a portion of said combined cooler-mufii'e assembly.

10. An electric circuit interrupter as set forth in claim 8 wherein said interrupter also includes a second combined cooling and muffiing portion constructed substantially similar to said first combined cooler-muffle portion immediately following said second expansion chamber.

'11. An electric circuit interrupter as set forth in claim 11, said circuit interrupter including enclosure means for said are discharge mnflie means comprising a generally box-like sheet metallic enclosure having a pair of parallel side-Walls, a pair of parallel top and bottom walls and an end wall, said end wall having openings therein in alignment with the openings of said combined heat exchange and mufiie portion, and means fixedly attaching said side walls of said enclosure to said arc discharge muffie means whereby pressure generated within said discharge muille is contained by said metallic enclosure.

12. A multipole electric circuit interrupter comprising:

(a) a plurality of arc establishing means disposed in side-by-sid'e relation and each having arc gas discharge openings therein in corresponding walls thereof whereby said arc discharge openings are disposed in a row;

(b) are discharge mufile means comprising a multicompartment metallic enclosure having an end wall, and opposed side top and bottom walls and partition means extending between said top and bottom walls parallel to said side walls and dividing said enclosure into a plurality of compartments corresponding in number to said number of arc establishing means;

() means supporting said metallic enclosure adjacent said are establishing means with said arc discharge openings of said are establishing means each positioned in and closing said open wall of one of said chambers of said enclosure;

(d) are discharge muflle means contained in each of said compartments of said enclosure and having arc discharge gas path means for passing arc discharge gases therethrough from said discharge openings of said are establishing means including arc discharge openings in said end wall. i1'3. An electric circuit interrupter as set forth in claim 12, at least said side walls of said enclosure being extended and overlapping portions of said arc establishing means and means rigidly attaching said side wall extensions to said arc establishing means whereby to rigidly interconnect said discharge muffle to said are establishing means to provide a unitary rigid assembly.

References Cited UNITED STATES PATENTS 1,984,396 12/ 1934 Clerc. 2,133,158 10/1938 Vet Planck et al. 2,272,214 2/ 41942 Linde. 2,457,002 12/ 1948 Spiro. 3,005,892 10/ 1961 Yarrick 200-'-l44 3,025,376 3/ 1962 Yarrick 200-444 3,265,842 8/ 1966 Pokorny 200144 ROBERT S. MACON, Primary Examiner.

US. Cl. XJR. 

1. AN ELECTRIC CIRCUIT INTERRUPTER COMPRISING MEANS FOR ESTABLISHING AN ARC AND ARC DISCHARGE MUFFLE MEANS, SAID ARC DISCHARGE MUFFLE MEANS COMPRISING: (A) A FIRST HEAT EXCHANGE PORTION COMPRISING A PLURALITY OF RELATIVELY CLOSELY SPACED FLAT METALLIC PLATES EXTENDING PARALLEL TO EACH OTHER IN CLOSELY SPACED RELATION IN A ROW, EACH OF SAID PLATES EXTENDING PARALLEL TO THE DIRECTION OF FLOW OF GASES FROM SAID ARC WHEREBY SAID ARC GASES ARE CONSTRAINED TO PASS BETWEEN SAID PLATES IN CLOSE THERMAL CONTACT WITH ADJACENT SIDE SURFACES OF SAID PLATES; (B) A PLURALITY OF ARC DIFFUSER PLATE PORTIONS, SAID ARC DIFFUSER PORTIONS COMPRISING A SERIES OF FLAT SHEET METALLIC MEMBERS EXTENDING AT AN ANGLE TO SAID PLATE OF SAID FIRST HEAT EXCHANGE PORTION AND CLOSELY ADJACENT THE EXIT POINT FOR GASES PASSING BETWEEN SAID FIRST HEAT EXCHANGE PLATES WHEREBY GASES PASSING BETWEEN SAID HEAT EXCHANGE PLATES STRIKE SAID DIFFUSER PLATE MEMBERS AND ARE CAUSED TO ASSUME A TURBULENT CONDITION FOR INTERMIXING COOL PORTIONS OF SAID GAS WITH MORE HEATED PORTIONS THEREOF, AND 